docs: def is_unitless(ds, variable):
      '''
      Returns true if the variable is unitless
  
      Note units of '1' are considered whole numbers or parts but still represent
      physical units and not the absence of units.
  
      :param netCDF4.Dataset ds: An open netCDF dataset
      :param str variable: Name of the variable
      '''
      units = getattr(ds.variables[variable], 'units', None)
      return units is None or units == ''